This report includes the test results on aggregates from four taconite strata from the Mesabi iron range of Minnesota for concrete qualities including Los Angeles Rattler (LAR), absorption, flatness and elongation, magnesium sulfate, ASTM C 1260, and ASTM C 1293. The strata are identified as LC-8 Bed from United Taconite, LC-5 Bed from Ispat Inland/Mittal Steel (Laurentian Pit), LS-2 Bed from Ispat Inland/Mittal Steel (Laurentian Pit), and LUC Bed from United Taconite. A granite source, known to have moderately low expansion characteristics was also tested for comparison. All ledges tested well for Los Angeles Rattler and magnesium sulfate soundness. Ledges LS-2, LC-8, and LS-2 had excellent results for ASTM C 1260 and ASTM C 1293 expansion, while the LC-5 ledge performed very poorly. The Coal Creek fly ash used in the ASTM C 1293 tests mitigated ASR expansions much better than the slag mixes. As with any natural aggregate source, the physical and chemical properties of the taconite ledges vary. Because of the high variation in expansion potential, each potential concrete strata should be tested within a mine using ASTM C 1293. A Quality Control plan should be developed for each source. Specific gravity may be used to screen out potential deleterious strata, and should be performed frequently, perhaps on each blast. ASTM C 1260 tests should also be used on a frequent basis.
